Magnetic junk basket assembly for drill strings



G. C. CROOKS Dec. 11, 1962 MAGNETIC JUNK BASKET ASSEMBLY FOR DRILL STRINGS Filed April 7, 1960 United States Patent O 3,067,821 MAGNETIC JUNK BASKET ASSEMBLY FOR DRILL STRINGS George Carl Crooks, Red Deer, Alberta, Canada Filed Apr. 7, 1960, Ser. No. 20,607 12 Claims. (Cl. 166-99) My invention relates to magnetic junk baskets adapted to be utilized with conventional drill strings.

During the drilling of oil wells and the like, metallic particles and pieces from the drill bit often collect at the bottom of the drill hole and interfere with the drilling operation. Particularly such metallic junk often becomes jambed at the bottom :of the hole and if an attempt is made to drill past this material, serious damage may occur to the drill bit assembly.

I have overcome these disadvantages by providing a magnetic junk basket which can be lowered down upon the end of the drill string and can pick tup the metallic pieces by means of a magnet incorporated therein or, alternatively, can core past jambed pieces which are thus loosened so that they can `be picked up magnetically or mechanically by the basket and then raised to the surface.

The principal object and essence of my invention is therefore to provide a junk basket assembly consisting of a retractable magnet within a casing, said magnet being retractable after it has encountered the metallic junk and which also incorporates a plurality of inwardly biased catching iingers which spring inwardly to span the base of the casing after the magnet has been retracted thus preventing the metallic junk from becoming disengaged fro the magnet during the raising operation.

A further object of my invention is to provide a del vice `of the character herewithin described which includes a coring bit upon the end of the assembly which can be used, after the magnet has been retracted within the casing, to core past any jambed metallic pieces in the drill hole so that these pieces can either be picked up by the magnei or held mechanically by the catching fingers which, of course, are exposed once the magnet has been withdrawn into the casing,

Another object of my invention is to provide a device of the character herewithin described which is readily adapted for use with a conventional drill string.

A further object of my invention is to provide a device of the character herewithin described in which the extension of the magnet can be varied within limits.

Still another object of my invention is to provide a device of the character herewithin described which is simple in construction, economical in operation, and otherwise well suited for the purpose for which it is designed.

With the Lforegoing objects in view, and such other objects and advantages as will become apparent to those skilled in the art to which this invention relates as this specification proceeds, my invention consists essentially in the arrangement and construction of parts all as hereinafter more particularly described, reference being had to the accompanying drawings in which:

FIGURE l is a longitudinal sectional view ofmy device.

FIGURE 2 is an enlarged side elevation of the catching finger component.

FIGURE 3 is an enlarged plan elevation of the catching finger component.

lFIGURE 4 is an enlarged side elevation of the coring assembly, per se.

FIGURE 5 is an enlarged partial plan view of the coring assembly per se.

`In the drawings like characters of reference indicate corresponding parts in the different figures.

Proceeding therefore to describe my invention in de-A tail, reference should be made to the accompanying ice?,

draw-ings and in particular to FIGURE 1. The device consists of an elongated cylindrical casing 10 being screwthreaded as at 11 at the upper end 12 thereof to take a cylindrical adaptor portion 13 which in turn is screw# threaded as at 14 so that the device can readily be assembled to the lower end of a conventional drill string (not illustrated).

The casing 10 also includes Kan extension 15 screw` threadably secured to the lower end 16 of the casing, and this extension includes an inwardly extending shouldered portion '17', the purpose of which will hereinafter be described.

A magnet carrying assembly collectively designated 18 is adapted to slide lengthwise within the cylindrical casing and consists of a shearing head 19 cylindrical in configuration to the lower end 20 of which is screwthreadably secured a cylindrical body portion 21.

A coil spring 22 surrounds the upper end of the body portion and reacts between the aforementioned shouldered portions 17 and the underside 23 of the shearing head, thus normally maintaining the magnet carrying assembly retracted within the cylindrical casing and against the shoulder 24 of the lower end of the adaptor 13.

However, it is designed to extend this magnet holding assembly as will hereinafter be described, and in this connection I have provided a plurality of radial grooves 25 around the wall of the shearing head 19 and a plurality of drilled apertures 26 through the wall of the cylindrical casing 10. These drilled apertures are provided with tapered plugs 27 and are adapted to receive a shear pin 28 which may engage either of the apertures 26 and either of the annular grooves 25 thus giving a certain adjustment to the amount of extension of the magnet holding assembly within limits.

It will be appreciated that the magnet holding assembly has to be moved downwardly within the cylindrical casing against the pressure of the spring 22 whereupon the shear pin 28 is engaged within the relevant aperture 26 and the relevant groove 25thus holding the magnet holding assembly in the extended position against the pressure of spring 22.

Screwthreadably secured to the lower end 29 of the body portion 21 is a magnetic component comprising a cylindrical shell 30 having an inwardly tapered lower end 31. The magnetic elements 32 are held within the shell 30 and pole pieces or cups 33 engage the lower end of the magnetic elements all of which are held within the shell 30 by the tapered configuration of the lower end 31 thereof and the corresponding tapered configuration of t-he pole caps 33.

This magnetic assembly is screwthreadably secured to the lower end of the body portion 21 and is mechanically integral therewith. v

It will be appreciated, however, that both the adaptor 13, the shear head 19, the body portion 21, and the mag-l netic assembly 32 are apertured centrally to provide for the circulation of the drilling medium whether it be mud or air.

Surrounding the lower end 29 of the body portion 21, when said body portion is in the extended position as shown in FIGURE l, are two sets of catching fingers collectively designated 34 being held in the desired posi-- tion by a coring bit assembly collectively designated 3S.

Reference should be made to FIGURES 2 and 3 of the drawings in which I show details of the catching finger components.

Each component comprises an annular or cylindrical cage 36, the wall 37 of which is castellated thus forming a plurality of equally spaced apertures 38 around the upper edge thereof.

Within these apertures I have pivoted catching iingers 39 by means of pins 40, these catching fingers being' 3 spring loaded (not illustrated) so that normally they are biased inwardly towards .the center 41 of the cage.

It will be observed that alternate fingers specifically designated 39' extend substantially towards `the center 41 when in the extended position whereas the intermediate fingers 39" ex-tend part way, thus giving almost cornplete coverage -to the area when the fingers are in the extended position as shown in FIGURE 3.

However, when in the position shown in FIGURE 1, these fingers are in a substantially vertical plane resting against the lower end of the body portion 21 and are held in this position until the body portion is retracted, whereupon they spring inwardly to take up the position shown in FIGURE 3.

I have provided two sets of these lingers, one above the other as clearly shown in FIGURE l, and the cages and the lingers are merely slipped on around the lower end of the body portion when the device is assembled.

The aforementioned coring bit assembly consists of a cylindrical casing 42 screwthreadably secured as at 43 to the lower end of the casing extension and adapted to hold the aforementioned catching linger components against the lower end of the casing as clearly shown in -FIGURE l.

The coring teeth 44 are cemented to the lower end 45 ofthe casing 42 and are adapted to be situated just above the lowermost end of the magnetic component when same is in the extended position.

In operation, the magnet carrying assembly is extended against pressure of spring 22 and the shear pin 28 is placed in the desired position.

The catching linger components are then placed over the distal end of the body 21 of the magnet carrying assembly with the lingers in the substantially vertically position as shown in FIGURE l.

The coring bit assembly is then placed over the cages of the catching finger components and screwthreadably secured to the portion 15 of the casing as hereinbefore described.

'I'he entire device is then secured by the adaptor 13 to the lower end of the drill string and lowered into the well hole.

When 'the tool is near the bottom of the hole, the pumps are started forcing the circulation medium (mud or air) through the entire assembly thus washing away any formation cuttings or loose formation cavings from the top of the junk that is to be retrieved at the bottom of the hole.

The tool is then lowered slowly until, by predetermined pipe measurement, it is engaging the top of the junk at the bottom of the hole. Additional weight of the drilling string is applied to the tool and subsequently the magnet assembly extending therebelow. This .breaks the shear pin 28 thus causing spring 22 to force the magnet carrying assembly upwardly within the cylindrical casing and clear of the bottom of said casing.

The junk, which adheres to the pole caps 33, is drawn upwardly within the casing above the catching lingers which, of course, extend radially inwardly across the varea once occupied by the lower end 29 of the body v21. This prevents any metallic junk which might become disengaged from the pole caps, from leaving the interior of the casing.

In many cases the metallic junk may have become wedged in the hole and the magnet will not dislodge same. With the magnet in position above the catchers, the operator now has another opportunity to retrieve the junk iby using the device to cut a small core and force the junk up into the catchers. With the magnet retracted, the drilling string is rotated so that suicient core is cut to assure that the junk is -forced up into the catchers which, of course, retract to let it pass.

The metal junk is either held by the magnet orcaught with the lingers of the catchers so vthat the tool can be withdrawn from-the hole by the operator.

It will therefore be seen that two independent fishing operations can be performed with a single run of this tool, thus facilitating considerably the clearing of such drilled holes.

Since various modifications can be made in my invention as hereinabove described, and many apparently widely different embodiments of same made within the spirit and scope of the claims without departing from such spirit and scope, it is intended that all matter contained in the accompanying specification shall be interpreted as illustrative only and not in a limiting sense.

What I claim as my invention is:

1. A magnetic junk basket assembly for use with drill strings, comprising in combination an elongated cylindrical casing, means on one end thereof adapted -to secure said casing to the lower end of a drill string, a magnet carrying assembly movable lengthwise within said casing, said magnet carrying assembly having magnetic means on the lower end thereof, a spring loaded catching nger component secured to the other end of said casing and surrounding said magnet carrying assembly, a coring bit assembly secured to and surrounding the said other end of said casing and below said catching linger component and adapted to secure said component to said other end of said casing, said catching linger component comprising a cylindrical cage adapted to be secured to said other end of said casing, a plurality of lingers pivoted to the wall of said cage and normally being biased inwardly towards the center of said cage, thus adapted to be held retracted when said magnet carrying assembly is extended in said casing but adapted to extend to span radially the area occupied by said magnet carrying assembly when same is retracted within said casing, spring means reacting between said magnet carrying assembly and said casing, normally retracting said magnet carrying assembly into said casing, and shearable means extending between said casing and said magnet carrying assembly normally holding said magnet carrying assembly extended from said casing against the pressure of said spring.

2. The device according to claim l in which said magnetic means extends below said coring assembly when said magnet carrying assembly is extended, said magnetic means retracting above said catching finger component when said magnet carrying assembly is retracted.

3. The device according to claim l in which said magnet carrying assembly comprises a shearing head, and a body portion secured by one end thereof to and extending Ibelow said shearing head, said magnetic means being secured to the other end of said body portion, -and comprising magnetic elements, a holder for said magnetic elements secured to said other end of said body portion, and -pole caps also held by saidholder.

4. The device according to claim l which includes alterna-te lingers extending substantially towards the center of said cage.

5. The device according to claim 2 in which said magnet carrying assembly comprises a shearing head, and a body portion secured by one end thereof to and extending below said shearing head, said magnetic means being secured to the other end of said body portion, and comprising magnetic elements, a holder for said magnetic elements secured to said other end of said body portion, and pole caps also held by said holder.

6. The device according to claim 2 which includes alternate fingers extending substantially -towards the center of said cage.

7. The device according to claim 5 which includes alternate fingers extending substantially -towards the center of said cage.

v8. The device according to claim 5 in which said casing includes a shouldered portion extending inwardly thereof, saidspring reactingbetween'said shouldered portion and the underside of said shearing head and surrounding said body portion.

9. The device according .to claim 8 in which said shear- Iing head has a plurality of annular grooves formed therearound, said casing has a plurality of shear pin holding apertures formed therethrough, -said shearable means comprising a shear pin adapted to engage a selected one of said apertures and a selected one of said annular grooves thereby controlling the extension of said magnetic means within limits.

10. The device according to claim 3 which includes alternate fingers extending substantially towards the center of rsaid cage.

1l. The device according lto claim 3 in which said casing includes a shouldered portion extending inwardly thereof, said sprin-g reacting between said shouldered portion and the underside of said shearing head and surrounding said body portion.

12. The device according to claim 11 in which said shearing head has a plurality of annular -grooves formed therearound, lsaid casing has a plurality of shear pin holding apertures formed therethrough, said shearable means comprising a shear pin adapted to engage a selected one of said apertures and a rselected one of said -annular grooves thereby controlling the extension of said magnetic means within limits.

Ballew et al. Nov. 3, 1953 Fortenberry Jan. 25, 1955 

